On 23 March, 1534, Parliament passed the Act of Succession, vesting the succession of the English Crown in the children of King Henry VIII and Anne Boleyn. This act, effectively, set Princess Elizabeth first in line for the throne, declaring Princess Mary a bastard. It was also proclaimed that subjects, if commanded, were to swear an oath to recognizing this Act as well as the King's supremacy. People who refused to take the oath, including Sir Thomas More, were charged with treason.

This Act was overridden by the Act of Succession, 1536, which made the children of Jane Seymour first in line for the throne, declaring the King's previous marriages unlawful, and both princesses illegitimate.